The leaves remind me of Veratrum, they send a flower spike up but can be very slow to flower. I would think it had flowered within 50 years though!
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If the thing showing in the middle is a seed pod then that seems to rule it out, unless it's about to send up a flower spike. Keep an eye on it, I have Veratrum nigrum and it's sending up a stem for the first time which doesn't look to have any flowers, yet. I've had it for around 7 years, and it was about 7 years old when I bought it!
It also bears resemblance to a Helleborine orchid, Epipactis .
